Axial Loading Effect on the Behavior of Large Helical Pile Groups in Sandy Soil

There are a lot of the parameters which affect pile group behavior in soil. One of these factors is the distance of piles from each other. The impact of distance on pile groups in sand has been investigated through some researches, whereas most of them have not represented an exact estimation according to the continuous change of the distance in sand. Moreover, most of previous investigations have considered two piles as a perfect group. Since two-pile group has the least interaction effect among piles, it cannot suitably demonstrate the influence of spacing. In this lecture, several 4-pile groups modeled with different spacing were subjected to axial loading in laboratory. The pile groups were free-head with length to diameter ratio of 13.5. The piles are designed in a way which the shaft resistance of piles can be completely mobilized through the test. Then, the bearing capacities of pile groups are measured and compared with the single pile's resistance in order to calculate the efficiency coefficient of the groups. It is revealed that the distance is noticeably effective in efficiency factor and this effectiveness, non-linearly decreases by increase of spacing. The results show that the efficiency coefficient is changing between almost 1 and 1.4.

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MODELISASI ANALISIS NUMERIK GAYA LATERAL PADA ELEVATED REINFORCED CONCRETE PILE CAP PADA TANAH NON KOHESIF

Jurnal Muara Sains, Teknologi, Kedokteran dan Ilmu Kesehatan ◽

10.24912/jmstkik.v5i1.8984 ◽

2021 ◽

Vol 5 (1) ◽

pp. 111

Author(s):

Alvin Lo ◽

Hendy Wijaya ◽

Amelia Yuwono

Keyword(s):

Reinforced Concrete ◽

Numerical Analysis ◽

Sandy Soil ◽

Pile Group ◽

Lateral Force ◽

Pile Groups ◽

The Road ◽

Concrete Pile ◽

Earthquake Force ◽

Pile Cap

Bridges are construction structures that are built to connect parts of the road that are cut off by obstacles such as deep valleys, irrigation channel paths. In order to build a bridge, a strong, economical and easy to build foundation is needed to carry gravity loads and also earthquake force. A common problem encountered in bridge foundation is the occurrence of erosion around the piles due to scouring of water which causes exposing some portion of the piles, which are often referred as elevated reinforced concrete pile-cap foundations. In this study, a numerical analysis of pile groups on elevated reinforced concrete pile-cap foundations is carried out with lateral forces on sandy soil to see the ductility behavior of piles using geotechnical-based programs and to compare the results with the previous studies. The analysis includes the pilecap model and the soil-to-pile interaction and also considers the pile group effect. The analysis was carried out to see the structural and geotechnical conditions on the ductility behavior of a partially embedded piles on sandy soil. The result obtained is a comparison of the ductility and overstrength values that can be used as a consideration in designing elevated reinforced concrete pile-cap foundations.Keywords: Elevated RC pile-cap foundations; numerical analysis; lateral force; ductility AbstrakJembatan adalah struktur konstruksi yang dibangun untuk menghubungkan bagian jalan yang terputus oleh rintangan-rintangan seperti lembah yang dalam, alur saluran irigasi. Untuk membangun sebuah jembatan, diperlukan fondasi yang kuat, ekonomis dan mudah untuk dibangun untuk memikul beban dari jembatan dan juga gaya gempa. Masalah yang umum ditemui pada konstruksi fondasi jembatan adalah terjadinya erosi pada sekitar fondasi dikarenakan gerusan air yang menyebabkan tanah terangkat dan memperlihatkan sebagian tiang fondasi, yang sering disebut dengan elevated reinforced concrete pile-cap foundations. Pada penelitian ini dilakukan analisis secara numerik terhadap kelompok tiang pada elevated reinforced concrete pile-cap foundations yang dibebani gaya lateral pada tanah berpasir untuk melihat perilaku daktilitas tiang dengan bantuan program berbasis geoteknik dan membandingkan dengan hasil penelitian terdahulu. Analisis menyertakan model kepala tiang dan hubungan antara tanah dengan tiang serta mempertimbangkan efek kelompok tiang. Analisis dilakukan untuk melihat kondisi struktural dan geoteknikal pada perilaku daktilitas fondasi yang ditanam sebagian pada tanah pasir. Hasil yang didapatkan adalah perbandingan nilai daktilitas dan overstrength yang dapat digunakan sebagai pertimbangan dalam mendesain elevated reinforced concrete pile-cap foundations.

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Assessing the Effects of Length, Slope and Distance between Piles on the Bearing Capacity of a Pile Group under Axial Loading in Granular Soil

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.1352 ◽

2017 ◽

Vol 7 (5) ◽

pp. 1894-1899

Author(s):

A. Firoozfar ◽

A. Rostami ◽

H. Ghaderi ◽

H. Zamani ◽

A. Rostamkhani

Keyword(s):

Bearing Capacity ◽

Axial Loading ◽

Pile Group ◽

Granular Soils ◽

Deep Foundations ◽

Pile Groups ◽

Finite Element Software ◽

Bedrock Depth ◽

Exact Effect ◽

Technical Capacity

Piles are usually made of steel, concrete, reinforced concrete or wood, used to enhance the ground’s bearing capacity in order to enable the construction of deep foundations, also called pile foundations. However, the exact effect of the complex interaction between the piles and the surrounding soil has not adequately been investigated yet. Considering the increased application of the technique recently, further analysis is essential for achieving the highest economic and technical capacity. Using fewer piles or shorter piles and allowing greater distances between pile groups, results to reduced construction. However, other restrictions such as high groundwater level, bedrock depth and the limited size of the foundation are also to be considered. The issue of optimal pile layout is further investigated in the current paper employing Plaxis, a finite element software, for modeling purposes and considering axial loadings in granular soils. Results are shown and further discussed.

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